By way of example, a method for determining individual quantum absorption events in a radiation converter for converting individual quanta of ionizing radiation incident on is known from R. Ballabriga et al.: “The Medipix3 Prototype, a Pixel Readout Chip Working in Single Photon Counting Mode with Improved Spectrometric Performance”, 2006 IEEE Nuclear Science Symposium Conference Record. In the known method, that analog signal with the respectively strongest signal strength is associated with the absorption of a quantum. In this case, weaker signal strengths are not considered to be absorption events. A comparison of the respective analog signals of the signals corresponding to the individual pixels and the sums of the signals of in each case four adjacent pixels is carried out in this case by way of comparators.
In this case, it is disadvantageous that the number of quanta absorbed by the radiation converter cannot be determined satisfactorily. By way of example, due to the photoelectric effect and/or Compton scattering, it is possible for individual quantum to cause a plurality of quantum absorption events in different pixels. In these circumstances, it is possible that none of the signal strengths of the analog signals of a plurality of quantum absorption events belonging to a single quantum suffice will register the absorption of the quantum. In this case, no quantum is counted despite a quantum being absorbed. Furthermore, it is possible for two or more of the signal strengths of the analog signals of a plurality of quantum absorption events belonging to a single quantum to be registered. In this case, a plurality of quanta are spuriously registered, although only a single quantum has been absorbed by the radiation converter.
If energy of the quanta is to be determined simultaneously in the method, the cases described above inevitably lead to the energy of the absorbed quantum being determined incorrectly.